In general, construction equipment, such as a wheel loader, mainly performs excavation or a loading task or a transportation task of accumulated earth and sand. The construction equipment includes a cooling fan unit which drives a cooling fan in order to cool hydraulic oil, cooling water of an engine, or gear shift lubricating oil of a transmission, and a brake unit for braking a vehicle, and hydraulic oil discharged from one pump is supplied to drive the cooling fan unit and the brake unit.
More particularly, the hydraulic oil discharged from one pump is primarily supplied to the brake unit by a main control value to accumulate a predetermined pressure in the brake unit, and when the pressure accumulated in the brake unit is equal to or greater than a reference charging pressure, the hydraulic oil is supplied to the cooling fan unit and is controlled by a cooling fan-brake control system.
FIG. 1 is a diagram illustrating a cooling fan-brake control system of construction equipment, and FIG. 2 is a graph illustrating overspeed of the cooling fan after a brake is charged in the cooling fan-brake control system of FIG. 1.
As illustrated in FIGS. 1 and 2, the cooling fan-brake control system applied to the construction equipment in the related art includes a pressure detection unit 1 detecting pressure of a brake, a temperature detection unit 2 detecting a temperature of an engine and hydraulic oil of the engine, a controller 6 receiving pressure information and temperature information from the pressure detection unit 1 and the temperature detection unit 2, respectively, and controlling a flow rate of hydraulic oil discharged from a pump 5 so that the hydraulic oil is supplied from the pump 5 to each of a cooling fan unit 3 and a brake unit 4, and a main control valve 7 supplying the hydraulic oil to each of the cooling fan unit 3 and the brake unit 3 under a control of the controller 6.
Here, the controller 6 may receive a signal from the temperature detection unit 2 to operate the pump 5, and the hydraulic oil discharged from the pump 5 may rotate the cooling fan of the cooling fan unit 3 through the main control valve 7, thereby cooling the engine or the hydraulic oil. Further, the controller 6 may receive a signal from the pressure detection unit 1 to operate the pump 5 so as to normally operate the brake, in addition to the operation of the cooling fan unit 3, and the hydraulic oil discharged from the pump 5 may make a pressure of the brake unit 4 be maintained at a predetermined value or more through the main control valve 7.
However, in the cooling fan-brake control system applied to the construction equipment in the related art, when the hydraulic oil discharged from the pump 5 is rapidly increased in order to charge a pressure of the brake unit 4 according to the operation of the brake unit 4 in the state where the cooling fan is being rotated by the hydraulic oil, the hydraulic oil with a high-pressure/high flow rate is temporarily supplied to the cooling fan unit 3 just after the charging of the brake, so that there is a problem in that the cooling fan is operated at overspeed and thus fuel efficiency deteriorates and noise is increased.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.